This invention is in the field of improving the water solubility of benzimidazole derivatives and other weak bases and providing pharmaceutical formulations of the same. Benzimidazole derivatives are useful for inhibiting the growth of cancers, tumors and viruses in mammals, particularly in humans and warm-blooded animals (U.S. Pat. Nos. 6,479,526; 5,880,144; 6,245,789; 5,767,138; 6,265,437). Certain benzimidazole derivatives used in combination with other compounds have been reported to be useful as fungicides (U.S. Pat. Nos. 3,954,993; 4,593,040; 5,756,500; 4,835,169; 4,980,346). However, benzimidazole derivatives, including carbendazim, are poorly water soluble. The projected oral dose of carbendazim for cancer treatment is up to several hundred mg per day which is far greater than its water solubility. Other weak bases suffer from the same lack of water solubility.
A method of improving the water solubility of benzimidazole derivatives and other weak bases and pharmaceutical formulations of the same is needed.